Preheat the oven: Preheat the oven to 350°F. Line a large baking sheet with parchment paper and set aside.
Mix the wet ingredients: In a large mixing bowl, combine the mashed bananas, peanut butter, honey, brown sugar, melted butter (or coconut oil), egg, and vanilla extract. Stir until well combined.
1 cup mashed ripe bananas, 1/2 cup creamy peanut butter, 2 Tbsp. honey, 2 Tbsp. brown sugar, 1/4 cup unsalted butter, 1 large egg, 1 tsp. vanilla extract
Add the dry ingredients: Add the oats, ground flaxseed, cinnamon, salt, and baking powder. Stir until everything is evenly incorporated, then fold in the mini chocolate chips.
2¼ cups oats, 2 Tbsp. ground flaxseed, 1/2 tsp. ground cinnamon, 1/2 tsp. salt, 1/2 tsp. baking powder, 1/2 cup mini chocolate chips
Scoop and shape: Scoop the cookie dough onto the prepared baking sheet, spacing the cookies about 2 inches apart. Gently press down on each cookie with your fingers or the back of a spoon to flatten into a cookie shape. These cookies won't spread much as they bake, so be sure to shape them to your desired thickness before baking. Press a few extra mini chocolate chips on top, if desired.
Bake: Bake for 15–16 minutes Start Timer, or until the cookies are set and lightly golden around the edges. Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.